The present invention relates to a method and apparatus for delivering a substance and particularly a pharmaceutical agent transdermally to a patient. More particularly, the invention is directed to a method and apparatus for delivering a pharmaceutical agent such as a vaccine to a patient through the stratum corneum.
The skin is made up of several layers with the upper composite layer being the epithelial layer. The outermost layer of the skin is the stratum corneum which has well known barrier properties to prevent molecules and various substances from entering the body and analytes from exiting the body. The stratum corneum is a complex structure of compacted keratinized cell remnants having a thickness of about 10-30 microns. The stratum corneum forms a waterproof membrane to protect the body from invasion by various substances and the outward migration of various compounds.
The natural impermeability of the stratum corneum prevents the administration of most pharmaceutical agents and other substances through the skin. Numerous methods and devices have been proposed to enhance the permeability of the skin and to increase the diffusion of various drugs through the skin so that the drugs can be utilized by the body. Typically, the delivery of drugs through the skin is enhanced by either increasing the permeability of the skin or increasing the force or energy used to direct the drug through the skin.
One example of a method for increasing the delivery of drugs through the skin include iontophoresis. Iontophoresis generally applies an external electrical field to ionize the drug, thereby increasing the diffusion of the drug through the skin. Iontophoresis can be difficult to control the amount and rate of drug delivery. Under some circumstances, iontophoresis can cause skin damage depending on the extent of ionization, the energy applied to ionize the drug and duration of the treatment.
Sonic, and particularly ultrasonic energy, has also been used to increase the diffusion of drugs through the skin. The sonic energy is typically generated by passing an electrical current through a piezoelectric crystal or other suitable electromechanical device. Although numerous efforts to enhance drug delivery using sonic energy have been proposed, the results generally show a low rate of drug delivery.
Another method of delivering drugs through the skin is by forming micropores or cuts through the stratum corneum. By penetrating the stratum corneum and delivering the drug to the skin in or below the stratum corneum, many drugs can be effectively administered. The devices for penetrating the stratum corneum generally include a plurality of micron size needles or blades having a length to penetrate the stratum corneum without passing completely through the epidermis. Examples of these devices are disclosed in U.S. Pat. No. 5,879,326 to Godshall et al.; U.S. Pat. No. 5,250,023 to Lee et al., and WO 97/48440.
Transdermal drug delivery is also known to use pulsed laser light to ablate the stratum corneum without significant ablation or damage to the underlying epidermis. A drug is then applied to the ablated area and allowed to diffuse through the epidermis.
The prior methods and apparatus for the transdermal administration of drugs has exhibited limited success. Accordingly, a continuing need exists in the industry for an improved device for the administration of various drugs and other substances.
The present invention is directed to a method and apparatus for the transdermal delivery of a substance, such as a drug, vaccine or other pharmaceutical agent, to a patient. In particular, the invention is directed to a method and apparatus for delivering a pharmaceutical agent to the stratum corneum of the skin to a sufficient depth where the pharmaceutical agent can be absorbed and utilized by the body. In embodiments where the pharmaceutical agent is a vaccine, the vaccine is introduced into the intradermal tissue below the stratum corneum where the vaccine can generate an immune response.
Accordingly, a primary object of the invention is to provide a method and apparatus for efficiently administering a pharmaceutical agent transdermally through the skin substantially without pain to the patient.
Another object of the invention is to provide an apparatus having a plurality of microneedles or blades for penetrating the stratum corneum of the skin for delivering a pharmaceutical agent or other substance to the skin.
A further object of the invention is to provide an apparatus for delivering a plurality of drugs transdermally to an animal either simultaneously or sequentially.
Another object of the invention is to provide a method for transdermally delivering one or more vaccines simultaneously or sequentially in small doses.
A further object of the invention is to provide a method and apparatus for the transdermal delivery of multiple vaccines without the need for vaccine reformulation or combination.
A still further object of the invention is to provide an apparatus for the transdermal delivery of a pharmaceutical agent having a plurality of microneedles for penetrating the stratum corneum and a coupling member for coupling with a supply container for supplying a pharmaceutical agent to the microneedles.
Another object of the invention is to provide an apparatus having a plurality of microneedles for penetrating the stratum corneum and an outer adhesive patch for adhesively attaching the apparatus to the skin of a patient.
Still another object of the invention is to provide a transdermal pharmaceutical delivery device having an array of microneedles for penetrating the stratum corneum of the skin, where the device has a channel in a bottom surface for directing a fluid containing a pharmaceutical agent from a source to the microneedles.
A further object of the invention is to provide a device for the transdermal delivery of a substance to a patient where the device has an array of microneedles and a dried substance, the dried substance being reconstituted by introducing a solvent or carrier through the device and then delivered to a patient.
These and other objects of the invention are substantially attained by providing an intradermal delivery device for introducing a substance into the skin of a patient. The device comprises a top wall having a top surface, a bottom surface, and at least one opening extending between the top and bottom surfaces. A bottom wall is coupled to the top wall and spaced therefrom to define a reservoir therebetween for containing the substance. The bottom wall has an inner surface and an outer surface which have a plurality of openings. A coupling member is attached to the top surface of the top wall for supplying the substance through the openings in the top wall and into the reservoir. A plurality of microneedles are coupled to the outer surface of the bottom wall and are in communication with the openings in the bottom wall for directing the substance from the reservoir to the skin of a patient. The microneedles have a length sufficient to penetrate the stratum corneum of the skin without piercing or passing completely through the epidermis. The actual length of the microneedles can vary to optimize the delivery for the particular substance being administered. For example, the microneedles for administering a vaccine can have a length to pass through the stratum corneum into the other skin layers where deposition of vaccine and/or adjuvant can generate a desired immune response. This would normally follow interaction or uptake with various mechanisms that produce such responses, for example, uptake and antigen processing by Langerhans cells.
The objects and advantages of the invention are further attained by providing an intradermal device for administering a pharmaceutical agent through the skin of a patient. The device comprises a substantially planar base having a top surface, a bottom surface and an opening extending between the top and bottom surfaces. A coupling member is attached to the top surface of the base for directing a fluid containing a pharmaceutical agent through the opening in the base and for coupling to a fluid source. A plurality of microneedles are attached to and extend from the bottom surface of the base and have a length sufficient to penetrate the stratum corneum of the skin. A plurality of channels are formed in the bottom surface of the base and extend from the opening outwardly toward an outer edge of the base. The channels are positioned between the microneedles for directing a fluid from the opening to the microneedles.
The objects of the invention are further attained by providing an intradermal delivery device for delivering a substance, such as a pharmaceutical agent, to a patient. The device comprises a syringe having a syringe barrel with an outlet tip and a plunger for dispensing a liquid in the syringe. A plurality of microneedles are coupled to the tip. The microneedles can have a length sufficient to penetrate the stratum corneum of the skin and have channels which extend through the microneedles for delivering the pharmaceutical agent to a patient.
Another object of the invention is to provide a method of administering a pharmaceutical agent through the skin of a patient which comprises providing an intradermal device having a body with a top surface, a bottom surface, and at least one opening extending between the top and bottom surfaces. A plurality of microneedles are attached to and extend from the bottom surface of the body and can have a length sufficient to penetrate the stratum corneum of the skin. The device contacts the skin of a patient and sufficient pressure is applied for the microneedles to penetrate the stratum corneum of the patient. A pharmaceutical agent or other substance is delivered to the microneedles so that the substance is absorbed through the skin.
The objects, advantages and other salient features of the invention will become apparent from the following detailed description which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention.